1. Field of the Invention
The subject invention relates to a gear for transmitting mechanical power.
2. Description of the Prior Art
Like all manufactured components, gears and their installation are subject to manufacturing tolerances. In the prior art, if gear teeth are too large or if a first gear and its mating gear are too close together, there is interference between the first gear and its mating gear. As a result, the gears do not mate smoothly and excessive friction occurs between the gears. In addition, backlash takes place when the gear teeth are too small or if a first gear and its mating gear are too far apart. As a result, the gears do not remain in continuous contact, and transmission of power is not smooth and constant.
Prior art gears, such as U.S. Pat. No. 4,184,380 disclose using a coating of resilient material on the gear teeth. The thickness of the coating increases the overall width of the tooth to take up backlash space and the resilient material of the coating compresses and is compressed or displaced as it encounters the mating gear to reduce interference friction.
Other gears in the prior art enable movement of the gear teeth relative to the outer periphery of the gear to prevent backlash while reducing interference friction. For example, US2007/0180943 discloses gear teeth integral with and extending radially out from the outer periphery and defining openings and slots enabling circumferential movement of the teeth relative to the outer periphery of the gear.
Prior art gears include a cam groove in the gear hub to provide a path of motion for another machine element. The presence of a cam groove limits the size and depth of slots and openings defined by the gear teeth to enable circumferential movement. The slots and openings are also limited in size and depth as the gear diameter decreases.
One type of gear in the prior art includes a hub that has an outer periphery and defines sockets about the outer periphery for retaining a gear tooth in each socket. Each socket extends from the outer periphery and into the hub and terminates at a socket end with a throat or waist that is narrower circumferentially than the socket end. A gear tooth is disposed in each socket and extends radially outward from each of the sockets and throat thereof to a top land surface. An example of such a gear is disclosed in U.S. Pat. No. 5,203,861 to Irwin et al., however each gear tooth is fixed and prevented from moving circumferentially thereby providing no accommodation for backlash.